Autosomal dominant insensitivity to pain with hyperplastic myelinopathy and autosomal dominant indifference to pain

Two forms of aberrant sensation to pain are described: autosomal dominant insensitivity to pain and autosomal dominant indifference to pain. With indifference to pain, the sensation is received by the peripheral nerves but not perceived at a cerebral level. With insensitivity to pain, there is an abnormality of the spinal or peripheral nerves that interferes with transmission of the sensations for pain and temperature. In a family with insensitivity to pain, electron microscopy of the sural nerves demonstrated a unique abnormality of myelin that we have termed hyperplastic myelinopathy. The unmyelinated C fibers were normal, while the medium-sized or large-sized myelinated fibers were involved, indicating the importance of the latter in pain sensation.